The minimum distance between homes and commercial wind turbines in Maine should be nearly doubled to 1,000 feet to limit the effect of noise on residents, a long-awaited state report is recommending.
Noise is the leading cause of complaints from those living near grid-scale wind projects. The effect of unwanted sound is the subject of ongoing scientific and policy debate around the world.
The report acknowledges that wind turbine noise is a real issue but calls it a complicated one that needs more research. It also recommends giving residents a chance to learn more about the details of projects before they are built.
Taken together, the report indicates that Maine is moving in the right direction with wind power but has learned lessons from past experiences.
The report examined wind noise regulations and research in Maine, other states and foreign countries. The work was conducted last year by John Kerry, Maine’s former energy director, at the Legislature’s request. It was released this week after being reviewed by the new energy director, Ken Fletcher, and receiving the approval of Gov. Paul LePage.
The 162-page report, however, will do little to calm passions about wind power in Maine.
The proposed minimum setback is longer than three football fields, but it’s still way too short, wind opponents say, to keep people from being disturbed by the noise, low-frequency sound pressure and vibrations that turbines and their blades spinning atop 300-foot towers can make under various wind conditions.
“That’s just too little to protect citizens,” said Karen Bessey Pease, a spokeswoman for the Friends of the Highland Mountains.
The group supports research suggesting a one-mile setback, Pease said.
Maine’s current minimum setback is based on turbine manufacturer guidelines for safety – not noise – and is 1.5 times the height of the tower. That’s between 582 and 615 feet on most current projects.
That’s far enough, according to Jeremy Payne, executive director of the Maine Renewable Energy Association. The wind industry will consider the new details but may oppose attempts to expand the distance to a 1,000-foot minimum, Payne said, because it’s arbitrary and ignores local topography and on-site conditions.
“We’re comfortable that the existing setbacks are protective of public safety and health,” he said.
Overall, the report is supportive of Maine’s policy goals, embodied in the Wind Energy Development Act of 2007, to build 2,000 megawatts of capacity by 2015. Maine currently has six large projects with a total capacity of 265 megawatts, or 13 percent of the goal. One is under construction, three have permits and seven are being developed.
The report also serves as a primer on the complex study of wind noise. It summarizes the types of sound, such as the “whooshing” associated with the pressure from blades slicing through the air, as well as low-frequency noise and even “infrasound,” which is below the common limit of human perception. Also explored is wind shear, a measure of how speed increases with height, and a common source of complaint when the wind is blowing more strongly at the turbine hub than on the ground.
The report also reviews various noise guidelines in other states and countries. Maine’s standards, which set limits of 55 dBA in the day and 45 dBA at night, apply to all large development projects, not just wind. Sound estimates and distances are based on computer modeling by acoustic engineers.
This process is controversial, however. The standard was challenged last year at the Maine Supreme Judicial Court but upheld. The report suggests requiring separate noise regulations for wind development.
Time has showed that some Maine residents living near turbines, even more than 1,000 feet away, have problems that have attracted national media attention. The most notable examples are at Mars Hill, where the Maine Department of Environmental Protection granted a sound-level variance; Freedom, where a small project was approved by the town before the state’s wind law took effect; and Vinalhaven, where a handful of neighbors suffer from turbine noise from a three-turbine community project.
“One thousand feet is really ludicrous,” said David Wylie, one of the abutters on Vinalhaven. “We’re 2,400 feet away, and it’s really unbearable. It shakes the house and goes through our bones and bodies.”
Wylie said the sound is so bad that he and his wife want to sell their home.
The report acknowledges problems at Mars Hill and Vinalhaven involving residents living within a half-mile of a turbine, such as the Wylies.
Sleep disturbance is the biggest complaint with wind noise, the report notes, but it also recognizes that some people simply are more sensitive to turbine noise, especially in quiet, rural areas.
The reports also recommends more public hearings and meetings, to let residents ask questions and know what to expect from wind projects. Some developers do this on their own, but the Maine DEP and the Land Use Regulation Commission have taken different approaches. LURC has held formal public hearings for most projects in the unorganized territories; the DEP hasn’t done so in the towns it covers.
These and other measures would improve Maine’s wind-energy siting law, Fletcher said, and could be incorporated this year either through agency rulemaking or a legislative resolve. However, Fletcher made it clear that the new administration supports wind power development and isn’t backing off from goals set during the administration of Gov. John Baldacci.
“There are some legitimate issues,” he said, “but ‘no’ is not a strategy.”
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